Sunshine Console is a C# library for simple ASCII output/input. It's intended to be very friendly to beginners that just want to put something on the screen (while still being powerful enough for larger ASCII projects). See the official site for usage examples.

Sunshine Console is built atop OpenTK, which can therefore be used for mouse input and accessing OpenGL and OpenAL, and various other features & functions. OpenTK has been ported to Windows, Mac OSX, GNU/Linux, *BSDs, Android, iOS, etc.